A gas turbine includes a rotor that rotates around an axis and a casing that covers this rotor. The rotor has a rotor shaft and a plurality of rotor vanes mounted on the rotor shaft. In addition, a plurality of stator vanes is provided on the inner side of the casing.
The rotor vane has a vane body extending in a radial direction based on the axis, a platform provided on the radially inner side of the vane body, and a vane root provided on the radially inner side of the platform. The vane body of the rotor vane is disposed inside a combustion gas flow path through which combustion gas passes. The platform defines a perimeter of the combustion gas flow path on the radially inner side. The vane root is fixed to the rotor shaft. The stator vane has a vane body extending in the radial direction based on the axis, an inner shroud provided on the radially inner side of the vane body, and an outer shroud provided on the radially outer side of the vane body. The vane body of the stator vane is disposed inside the combustion gas flow path through which the combustion gas passes. The inner shroud defines the perimeter of the combustion gas flow path on the radially inner side. The outer shroud defines the perimeter of the combustion gas flow path on the radially outer side. The casing has ring segments that face the rotor vanes in the radial direction based on the axis. These ring segments define the perimeter of the combustion gas flow path on the radially outer side.
Thus, each of the platform of the rotor vane, the outer shroud and the inner shroud of the stator vane, and the ring segment constitutes a flow path forming plate that defines the combustion gas flow path. These flow path forming plates are exposed to the high-temperature combustion gas. Therefore, the flow path forming plates are typically cooled with air etc.
For example, Patent Literature 1 below discloses an inner shroud of a stator vane that is one type of flow path forming plate. This inner shroud has a back-side passage extending along a back end surface, and a plurality of back end surface blow-out passages. The back-side passage communicate with the back end surface passage and open in the back end surface. In this inner shroud, cooling air flows into the back-side passage. This cooling air flows from the back-side passage into the back end surface blow-out passages. The cooling air having flowed into the back end surface blow-out passages flows out from openings of the back end surface blow-out passages in the back end surface.